Systems and methods for decoding light field image files

ABSTRACT

Systems and methods in accordance with embodiments of the invention are configured to render images using light field image files containing an image synthesized from light field image data and metadata describing the image that includes a depth map. One embodiment of the invention includes a processor and memory containing a rendering application and a light field image file including an encoded image and metadata describing the encoded image, where the metadata comprises a depth map that specifies depths from the reference viewpoint for pixels in the encoded image. In addition, the rendering application configures the processor to: locate the encoded image within the light field image file; decode the encoded image; locate the metadata within the light field image file; and post process the decoded image by modifying the pixels based on the depths indicated within the depth map to create a rendered image.

CROSS-REFERENCE TO RELATED APPLICATION

The present invention claims priority to U.S. Provisional ApplicationSer. No. 61/540,188 entitled “JPEG-DX: A Backwards-compatible, DynamicFocus Extension to JPEG”, to Venkataraman et al., filed Sep. 28, 2011,the disclosure of which is incorporated herein by reference in itsentirety.

FIELD OF THE INVENTION

The present invention relates to decoding of image files and morespecifically to the decoding of light field image files.

BACKGROUND

The ISO/IEC 10918-1 standard, more commonly referred to as the JPEGstandard after the Joint Photographic Experts Group that developed thestandard, establishes a standard process for digital compression andcoding of still images. The JPEG standard specifies a codec forcompressing an image into a bitstream and for decompressing thebitstream back into an image.

A variety of container file formats including the JPEG File InterchangeFormat (JFIF) specified in ISO/IEC 10918-5 and the Exchangeable ImageFile Format (Exif) and can be used to store a JPEG bitstream. JFIF canbe considered a minimal file format that enables JPEG bitstreams to beexchanged between a wide variety of platforms and applications. Thecolor space used in JFIF files is YCbCr as defined by CCIRRecommendation 601, involving 256 levels. The Y, Cb, and Cr componentsof the image file are converted from R, G, and B, but are normalized soas to occupy the full 256 levels of an 8-bit binary encoding. YCbCr isone of the compression formats used by JPEG. Another popular option isto perform compression directly on the R, G and B color planes. DirectRGB color plane compression is also popular when lossless compression isbeing applied.

A JPEG bitstream stores 16-bit word values in big-endian format. JPEGdata in general is stored as a stream of blocks, and each block isidentified by a marker value. The first two bytes of every JPEGbitstream are the Start Of Image (SOI) marker values FFh D8h. In aJFIF-compliant file there is a JFIF APP0 (Application) marker,immediately following the SOI, which consists of the marker code valuesFFh E0h and the characters JFIF in the marker data, as described in thenext section. In addition to the JFIF marker segment, there may be oneor more optional JFIF extension marker segments, followed by the actualimage data.

Overall the JFIF format supports sixteen “Application markers” to storemetadata. Using application markers makes it is possible for a decoderto parse a JFIF file and decode only required segments of image data.Application markers are limited to 64K bytes each but it is possible touse the same maker ID multiple times and refer to different memorysegments.

An APP0 marker after the SOI marker is used to identify a JFIF file.Additional APP0 marker segments can optionally be used to specify JFIFextensions. When a decoder does not support decoding a specific JFIFapplication marker, the decoder can skip the segment and continuedecoding.

One of the most popular file formats used by digital cameras is Exif.When Exif is employed with JPEG bitstreams, an APP1 Application markeris used to store the Exif data. The Exif tag structure is borrowed fromthe Tagged Image File Format (TIFF) maintained by Adobe SystemsIncorporated of San Jose, Calif.

SUMMARY OF THE INVENTION

Systems and methods in accordance with embodiments of the invention areconfigured to render images using light field image files containing animage synthesized from light field image data and metadata describingthe image that includes a depth map. One embodiment of the inventionincludes a processor and memory containing a rendering application and alight field image file including an encoded image and metadatadescribing the encoded image, where the metadata comprises a depth mapthat specifies depths from the reference viewpoint for pixels in theencoded image. In addition, the rendering application configures theprocessor to: locate the encoded image within the light field imagefile; decode the encoded image; locate the metadata within the lightfield image file; and post process the decoded image by modifying thepixels based on the depths indicated within the depth map to create arendered image.

In a further embodiment the rendering application configuring theprocessor to post process the decoded image by modifying the pixelsbased on the depths indicated within the depth map to create therendered image comprises applying a depth based effect to the pixels ofthe decoded image.

In another embodiment, the depth based effect comprises at least oneeffect selected from the group consisting of: modifying the focal planeof the decoded image; modifying the depth of field of the decoded image;modifying the blur in out-of-focus regions of the decoded image; locallyvarying the depth of field of the decoded image; creating multiple focusareas at different depths within the decoded image; and applying a depthrelated blur.

In a still further embodiment, the encoded image is an image of a scenesynthesized from a reference viewpoint using a plurality of lowerresolution images that capture the scene from different viewpoints, themetadata in the light field image file further comprises pixels from thelower resolution images that are occluded in the reference viewpoint,and the rendering application configuring the processor to post processthe decoded image by modifying the pixels based on the depths indicatedwithin the depth map to create the rendered image comprises rendering animage from a different viewpoint using the depth map and the pixels fromthe lower resolution images that are occluded in the referenceviewpoint.

In still another embodiment, the metadata in the light field image fileincludes descriptions of the pixels from the lower resolution imagesthat are occluded in the reference viewpoint including the color,location, and depth of the occluded pixels, and rendering an image froma different viewpoint using the depth map and the pixels from the lowerresolution images that are occluded in the reference viewpoint furtherincludes: shifting pixels from the decoded image and the occluded pixelsin the metadata to the different viewpoint based upon the depths of thepixels; determining pixel occlusions; and generating an image from thedifferent viewpoint using the shifted pixels that are not occluded andby interpolating to fill in missing pixels using adjacent pixels thatare not occluded.

In a yet further embodiment, the image rendered from the differentviewpoint is part of a stereo pair of images.

In yet another embodiment, the metadata in the light field image filefurther comprises a confidence map for the depth map, where theconfidence map indicates the reliability of the depth values providedfor pixels by the depth map, and rendering an image from a differentviewpoint using the depth map and the pixels from the lower resolutionimages that are occluded in the reference viewpoint further comprisesapplying at least one filter based upon the confidence map.

In a further embodiment again, the metadata in the light field imagefile further comprises an edge map that indicates pixels in the decodedimage that lie on a discontinuity, and rendering an image from adifferent viewpoint using the depth map and the pixels from the lowerresolution images that are occluded in the reference viewpoint furthercomprises applying at least one filter based upon the edge map.

In another embodiment again, the edge map identifies whether a pixellies on an intensity discontinuity.

In a further additional embodiment, the edge map identifies whether apixel lies on an intensity and depth discontinuity.

In another additional embodiment, the metadata in the light field imagefile further comprises a missing pixel map that indicates pixels in thedecoded image that do not correspond to a pixel from the plurality oflow resolution images of the scene and that are generated byinterpolating pixel values from adjacent pixels in the synthesizedimage, and rendering an image from a different viewpoint using the depthmap and the pixels from the lower resolution images that are occluded inthe reference viewpoint further comprises ignoring pixels based upon themissing pixel map.

In a still further embodiment again, the light field image file conformsto the JFIF standard and the encoded image is encoded in accordance withthe JPEG standard, the memory comprises a JPEG decoder application, andthe rendering application configures the processor to: locate theencoded image by locating a Start of Image marker within the light fieldimage file; and decode the encoded image using the JPEG decoder.

In still another embodiment again, the metadata is located within anApplication marker segment within the light field image file.

In a still further additional embodiment, the Application marker segmentis identified using the APP9 marker.

In still another additional embodiment, the depth map is encoded inaccordance with the JPEG standard using lossless compression, and therendering application configures the processor to: locate at least oneApplication marker segment containing the metadata comprising the depthmap; and decode the depth map using the JPEG decoder.

In a yet further embodiment again, the encoded image is an image of ascene synthesized from a reference viewpoint using a plurality of lowerresolution images that capture the scene from different viewpoints, themetadata in the light field image file further comprises pixels from thelower resolution images that are occluded in the reference viewpoint,the rendering application configures the processor to locate at leastone Application marker segment containing the metadata comprising thepixels from the lower resolution images that are occluded in thereference viewpoint, and the rendering application configuring theprocessor to post process the decoded image by modifying the pixelsbased on the depth of the pixel indicated within the depth map to createthe rendered image comprises rendering an image from a differentviewpoint using the depth map and the pixels from the lower resolutionimages that are occluded in the reference viewpoint.

In yet another embodiment again, the metadata in the light field imagefile includes descriptions of the pixels from the lower resolutionimages that are occluded in the reference viewpoint including the color,location, and depth of the occluded pixels, and rendering an image froma different viewpoint using the depth map and the pixels from the lowerresolution images that are occluded in the reference viewpoint furtherincludes: shifting pixels from the decoded image and the occluded pixelsin the metadata to the different viewpoint based upon the depths of thepixels; determining pixel occlusions; and generating an image from thedifferent viewpoint using the shifted pixels that are not occluded andby interpolating to fill in missing pixels using adjacent pixels thatare not occluded.

In a yet further additional embodiment, the image rendered from thedifferent viewpoint is part of a stereo pair of images.

In yet another additional embodiment, the metadata in the light fieldimage file further comprises a confidence map for the depth map, wherethe confidence map indicates the reliability of the depth valuesprovided for pixels by the depth map, and rendering an image from adifferent viewpoint using the depth map and the pixels from the lowerresolution images that are occluded in the reference viewpoint furthercomprises applying at least one filter based upon the confidence map.

In a further additional embodiment again, the metadata in the lightfield image file further comprises an edge map that indicates pixels inthe decoded image that lie on a discontinuity, and rendering an imagefrom a different viewpoint using the depth map and the pixels from thelower resolution images that are occluded in the reference viewpointfurther comprises applying at least one filter based upon the edge map.

In another additional embodiment again, the edge map identifies whethera pixel lies on an intensity discontinuity.

In a still yet further embodiment again, the edge map identifies whethera pixel lies on an intensity and depth discontinuity.

In still yet another embodiment again, the edge map is encoded inaccordance with the JPEG standard using lossless compression, and therendering application configures the processor to: locate at least oneApplication marker segment containing the metadata comprising the edgemap; and decode the edge map using the JPEG decoder.

In a still yet further additional embodiment, the metadata in the lightfield image file further comprises a missing pixel map that indicatespixels in the decoded image that do not correspond to a pixel from theplurality of low resolution images of the scene and that are generatedby interpolating pixel values from adjacent pixels in the synthesizedimage, and rendering an image from a different viewpoint using the depthmap and the pixels from the lower resolution images that are occluded inthe reference viewpoint further comprises ignoring pixels based upon themissing pixel map.

In still yet another additional embodiment, the missing pixel map isencoded in accordance with the JPEG standard using lossless compression,and the rendering application configures the processor to: locate atleast one Application marker segment containing the metadata comprisingthe missing pixel; and decode the missing pixel map using the JPEGdecoder.

An embodiment of the method of the invention includes locating anencoded image within an light field image file using a rendering device,decoding the encoded image using the rendering device, locating themetadata within the light field image file using the rendering device,and post processing the decoded image by modifying the pixels based onthe depths indicated within the depth map to create a rendered imageusing the rendering device.

In a further embodiment of the method of the invention, post processingthe decoded image by modifying the pixels based on the depths indicatedwithin the depth map to create the rendered image comprises applying adepth based effect to the pixels of the decoded image using the rendingdevice.

In another embodiment of the method of the invention, the depth basedeffect comprises at least one effect selected from the group consistingof: modifying the focal plane of the decoded image using the renderingdevice; modifying the depth of field of the decoded image using therendering device; modifying the blur in out-of-focus regions of thedecoded image using the rendering device; locally varying the depth offield of the decoded image using the rendering device; creating multiplefocus areas at different depths within the decoded image using therendering device; and applying a depth related blur using the renderingdevice.

In a still further embodiment of the method of the invention, theencoded image is an image of a scene synthesized from a referenceviewpoint using a plurality of lower resolution images that capture thescene from different viewpoints, the metadata in the light field imagefile further comprises pixels from the lower resolution images that areoccluded in the reference viewpoint, and post processing the decodedimage by modifying the pixels based on the depths indicated within thedepth map to create the rendered image comprises using the depth map andthe pixels from the lower resolution images that are occluded in thereference viewpoint to render an image from a different viewpoint usingthe rendering device.

Another further embodiment of the invention includes a machine readablemedium containing processor instructions, where execution of theinstructions by a processor causes the processor to perform a processinvolving: locating an encoded image within a light field image file,where the light field image file includes an encoded image and metadatadescribing the encoded image comprising a depth map that specifiesdepths from the reference viewpoint for pixels in the encoded image;decoding the encoded image; locating the metadata within the light fieldimage file; and post processing the decoded image by modifying thepixels based on the depths indicated within the depth map to create arendered image.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 conceptually illustrates the architecture of an array cameraconfigured to generate light field image files in accordance withembodiments of the invention.

FIG. 2 is a flow chart of a process for creating a light field imagefile including an image synthesized from light field image data and adepth map for the synthesized image generated using the light fieldimage data in accordance with an embodiment of the invention.

FIG. 3 is a process for creating a light field image file that conformsto the JFIF standard and that includes an image encoded in accordancewith the JPEG standard in accordance with an embodiment of theinvention.

FIG. 4 illustrates an APP9 Application marker segment of a light fieldimage file that conforms to the JFIF standard in accordance with anembodiment of the invention.

FIG. 5 illustrates a “DZ Selection Descriptor” contained within an APP9Application marker segment of a light field image file that conforms tothe JFIF standard in accordance with an embodiment of the invention.

FIG. 6 illustrates a “Depth Map, Camera Array and Auxiliary MapsSelection Descriptor” contained within an APP9 Application markersegment of a light field image file that conforms to the JFIF standardin accordance with an embodiment of the invention.

FIG. 7 illustrates a “Depth Map, Camera Array and Auxiliary MapsCompression Descriptor” contained within an APP9 Application markersegment of a light field image file that conforms to the JFIF standardin accordance with an embodiment of the invention.

FIG. 8 illustrates a “Depth Map Attributes” field within a “Depth MapHeader” contained within an APP9 Application marker segment of a lightfield image file that conforms to the JFIF standard in accordance withan embodiment of the invention.

FIG. 9 illustrates a “Depth Map Descriptor” field within a “Depth MapHeader” contained within an APP9 Application marker segment of a lightfield image file that conforms to the JFIF standard in accordance withan embodiment of the invention.

FIG. 10 illustrates a “Depth Map Data Descriptor” contained within anAPP9 Application marker segment of a light field image file thatconforms to the JFIF standard in accordance with an embodiment of theinvention.

FIG. 11 illustrates a “Camera Array Attributes” field within a “CameraArray Header” contained within an APP9 Application marker segment of alight field image file that conforms to the JFIF standard in accordancewith an embodiment of the invention.

FIG. 12 illustrates a “Camera Array Descriptor” field within a “CameraArray Header” contained within an APP9 Application marker segment of alight field image file that conforms to the JFIF standard in accordancewith an embodiment of the invention.

FIG. 13 illustrates an “Individual Camera Descriptor” contained withinan APP9 Application marker segment of a light field image file thatconforms to the JFIF standard in accordance with an embodiment of theinvention.

FIG. 14 illustrates “Individual Camera Data” within an APP9 Applicationmarker segment of a light field image file that conforms to the JFIFstandard in accordance with an embodiment of the invention.

FIG. 15 illustrates an “Individual Pixel Data Structure” within an APP9Application marker segment of a light field image file that conforms tothe JFIF standard in accordance with an embodiment of the invention.

FIG. 16 illustrates an “Auxiliary Map Descriptor” within an “AuxiliaryMap Header” contained within an APP9 Application marker segment of alight field image file that conforms to the JFIF standard in accordancewith an embodiment of the invention.

FIG. 17 illustrates an “Auxiliary Map Data Descriptor” within an APP9Application marker segment of a light field image file that conforms tothe JFIF standard in accordance with an embodiment of the invention.

FIG. 18 illustrates a network including at least one encoding deviceconfigured to capture light field image data and encode light fieldimage files and to share the light field image file with renderingdevices via a network in accordance with an embodiment of the invention.

FIG. 19 conceptually illustrates a rendering device configured by arendering application to render an image using a light field image file.

FIG. 20 is a flow chart illustrating a process for rendering an imageusing a light field image file in accordance with an embodiment of theinvention.

FIG. 21 conceptually illustrates a rendering device configured by arendering application to render an image using a light field image filecontaining an image and/or a map encoded in accordance with the JPEGstandard.

FIG. 22 is a flow chart illustrating a process for rendering an imageusing a light field image file that conforms to the JFIF standard andincludes an image encoded in accordance with the JPEG standard andmetadata describing the encoded image.

FIG. 23 is a flow chart illustrating a process applying depth dependenteffects to an encoded image contained within the light field image filebased upon a depth map contained within the light field image file inaccordance with an embodiment of the invention.

FIG. 24 is a flow chart illustrating a process for rendering an imagefrom a different viewpoint to a reference viewpoint of an imagecontained within a light field image file in accordance with anembodiment of the invention.

DETAILED DESCRIPTION

Turning now to the drawings, systems and methods for storing imagessynthesized from light field image data and metadata describing theimages in electronic files and for rendering images using the storedimage and the metadata in accordance with embodiments of the inventionare illustrated. A file containing an image synthesized from light fieldimage data and metadata derived from the light field image data can bereferred to as a light field image file. As is discussed further below,the encoded image in a light field image file is typically synthesizedusing a super resolution process from a number of lower resolutionimages. The light field image file can also include metadata describingthe synthesized image derived from the light field image data thatenables post processing of the synthesized image. In many embodiments, alight field image file is created by encoding an image synthesized fromlight field image data and combining the encoded image with a depth mapderived from the light field image data. In several embodiments, theencoded image is synthesized from a reference viewpoint and the metadataincludes information concerning pixels in the light field image that areoccluded from the reference viewpoint. In a number of embodiments, themetadata can also include additional information including (but notlimited to) auxiliary maps such as confidence maps, edge maps, andmissing pixel maps that can be utilized during post processing of theencoded image to improve the quality of an image rendered using thelight field image data file.

In many embodiments, the light field image file is compatible with theJPEG File Interchange Format (JFIF). The synthesized image is encoded asa JPEG bitstream and stored within the file. The accompanying depth map,occluded pixels and/or any appropriate additional information including(but not limited to) auxiliary maps are then stored within the JFIF fileas metadata using an Application marker to identify the metadata. Alegacy rendering device can simply display the synthesized image bydecoding the JPEG bitstream. Rendering devices in accordance withembodiments of the invention can perform additional post-processing onthe decoded JPEG bitstream using the depth map and/or any availableauxiliary maps. In many embodiments, the maps included in the metadatacan also be compressed using lossless JPEG encoding and decoded using aJPEG decoder. Although much of the discussion that follows referencesthe JFIF and JPEG standards, these standards are simply discussed asexamples and it should be appreciated that similar techniques can beutilized to embed metadata derived from light field image data used tosynthesize the encoded image within a variety of standard file formats,where the synthesized image and/or maps are encoded using any of avariety of standards based image encoding processes.

By transmitting a light field image file including an encoded image, andmetadata describing the encoded image, a rendering device (i.e. a deviceconfigured to generate an image rendered using the information withinthe light field image file) can render new images using the informationwithin the file without the need to perform super resolution processingon the original light field image data. In this way, the amount of datatransmitted to the rendering device and the computational complexity ofrendering an image is reduced. In several embodiments, rendering devicesare configured to perform processes including (but not limited to)refocusing the encoded image based upon a focal plane specified by theuser, synthesizing an image from a different viewpoint, and generating astereo pair of images. The capturing of light field image data and theencoding and decoding of light field image files in accordance withembodiments of the invention are discussed further below.

Capturing Light Field Image Data

A light field, which is often defined as a 4D function characterizingthe light from all direction at all points in a scene, can beinterpreted as a two-dimensional (2D) collection of 2D images of ascene. Array cameras, such as those described in U.S. patent applicationSer. No. 12/935,504 entitled “Capturing and Processing of Images usingMonolithic Camera Array with Heterogeneous Imagers” to Venkataraman etal., can be utilized to capture light field images. In a number ofembodiments, super resolution processes such as those described in U.S.patent application Ser. No. 12/967,807 entitled “Systems and Methods forSynthesizing High Resolution Images Using Super-Resolution Processes” toLelescu et al., are utilized to synthesize a higher resolution 2D imageor a stereo pair of higher resolution 2D images from the lowerresolution images in the light field captured by an array camera. Theterms high or higher resolution and low or lower resolution are usedhere in a relative sense and not to indicate the specific resolutions ofthe images captured by the array camera. The disclosures of U.S. patentapplication Ser. No. 12/935,504 and U.S. patent application Ser. No.12/967,807 are hereby incorporated by reference in their entirety.

Each two-dimensional (2D) image in a captured light field is from theviewpoint of one of the cameras in the array camera. A high resolutionimage synthesized using super resolution processing is synthesized froma specific viewpoint that can be referred to as a reference viewpoint.The reference viewpoint can be from the viewpoint of one of the camerasin a camera array. Alternatively, the reference viewpoint can be anarbitrary virtual viewpoint.

Due to the different viewpoint of each of the cameras, parallax resultsin variations in the position of foreground objects within the images ofthe scene. Processes for performing parallax detection are discussed inU.S. Provisional Patent Application Ser. No. 61/691,666 entitled“Systems and Methods for Parallax Detection and Correction in ImagesCaptured Using Array Cameras” to Venkataraman et al., the disclosure ofwhich is incorporated by reference herein in its entirety. As isdisclosed in U.S. Provisional Patent Application Ser. No. 61/691,666, adepth map from a reference viewpoint can be generated by determining thedisparity between the pixels in the images within a light field due toparallax. A depth map indicates the distance of the surfaces of sceneobjects from a reference viewpoint. In a number of embodiments, thecomputational complexity of generating depth maps is reduced bygenerating an initial low resolution depth map and then increasing theresolution of the depth map in regions where additional depthinformation is desirable such as (but not limited to) regions involvingdepth transitions and/or regions containing pixels that are occluded inone or more images within the light field.

During super resolution processing, a depth map can be utilized in avariety of ways. U.S. patent application Ser. No. 12/967,807 describeshow a depth map can be utilized during super resolution processing todynamically refocus a synthesized image to blur the synthesized image tomake portions of the scene that do not lie on the focal plane to appearout of focus. U.S. patent application Ser. No. 12/967,807 also describeshow a depth map can be utilized during super resolution processing togenerate a stereo pair of higher resolution images for use in 3Dapplications. A depth map can also be utilized to synthesize a highresolution image from one or more virtual viewpoints. In this way, arendering device can simulate motion parallax and a dolly zoom (i.e.virtual viewpoints in front or behind the reference viewpoint). Inaddition to utilizing a depth map during super-resolution processing, adepth map can be utilized in a variety of post processing processes toachieve effects including (but not limited to) dynamic refocusing,generation of stereo pairs, and generation of virtual viewpoints withoutperforming super-resolution processing. Light field image data capturedby array cameras, storage of the light field image data in a light fieldimage file, and the rendering of images using the light field image filein accordance with embodiments of the invention are discussed furtherbelow.

Array Camera Architecture

Array cameras in accordance with embodiments of the invention areconfigured so that the array camera software can control the capture oflight field image data and can capture the light field image data into afile that can be used to render one or more images on any of a varietyof appropriately configured rendering devices. An array camera includingan imager array in accordance with an embodiment of the invention isillustrated in FIG. 1. The array camera 100 includes a sensor 102 havingan array of focal planes 104 and which is configured to communicate witha processor 108. The processor is also configured to communicate withone or more different types of memory 110 that can be utilized to storeimage data and/or contain machine readable instructions utilized toconfigure the processor to perform processes including (but not limitedto) the various processes described below. The array camera 100 alsoincludes a display 112 that can be utilized by the processor 108 topresent a user interface to a user and to display an image renderedusing the light field image data. Although the processor is illustratedas a single processor, array cameras in accordance with embodiments ofthe invention can utilize a single processor or multiple processorsincluding (but not limited to) a graphics processing unit (GPU).

In the illustrated embodiment, the processor receives image datagenerated by the sensor and reconstructs the light field captured by thesensor from the image data. The processor can manipulate the light fieldin any of a variety of different ways including (but not limited to)determining the depth and visibility of the pixels in the light fieldand synthesizing higher resolution 2D images from the image data of thelight field. Sensors including multiple focal planes are discussed inU.S. patent application Ser. No. 13/106,797 entitled “Architectures forSystem on Chip Array Cameras”, to Pain et al., the disclosure of whichis incorporated herein by reference in its entirety.

In the illustrated embodiment, the focal planes are configured in a 5×5array. Each focal plane 104 on the sensor is capable of capturing animage of the scene. The sensor elements utilized in the focal planes canbe individual light sensing elements such as, but not limited to,traditional CIS (CMOS Image Sensor) pixels, CCD (charge-coupled device)pixels, high dynamic range sensor elements, multispectral sensorelements and/or any other structure configured to generate an electricalsignal indicative of light incident on the structure. In manyembodiments, the sensor elements of each focal plane have similarphysical properties and receive light via the same optical channel andcolor filter (where present). In other embodiments, the sensor elementshave different characteristics and, in many instances, thecharacteristics of the sensor elements are related to the color filterapplied to each sensor element.

In many embodiments, an array of images (i.e. a light field) is createdusing the image data captured by the focal planes in the sensor. Asnoted above, processors 108 in accordance with many embodiments of theinvention are configured using appropriate software to take the imagedata within the light field and synthesize one or more high resolutionimages. In several embodiments, the high resolution image is synthesizedfrom a reference viewpoint, typically that of a reference focal plane104 within the sensor 102. In many embodiments, the processor is able tosynthesize an image from a virtual viewpoint, which does not correspondto the viewpoints of any of the focal planes 104 in the sensor 102.Unless all of the objects within a captured scene are a significantdistance from the array camera, the images in the light field willinclude disparity due to the different fields of view of the focalplanes used to capture the images. Processes for detecting andcorrecting for disparity when performing super-resolution processing inaccordance with embodiments of the invention are discussed in U.S.Provisional Patent Application Ser. No. 61/691,666 (incorporated byreference above). The detected disparity can be utilized to generate adepth map. The high resolution image and depth map can be encoded andstored in memory 110 in a light field image file. The processor 108 canuse the light field image file to render one or more high resolutionimages. The processor 108 can also coordinate the sharing of the lightfield image file with other devices (e.g. via a network connection),which can use the light field image file to render one or more highresolution images.

Although a specific array camera architecture is illustrated in FIG. 1,alternative architectures can also be utilized in accordance withembodiments of the invention. Systems and methods for encoding highresolution images and depth maps for storage in electronic files inaccordance with embodiments of the invention are discussed below.

Capturing and Storing Light Field Image Data

Processes for capturing and storing light field image data in accordancewith many embodiments of the invention involve capturing light fieldimage data, generating a depth map from a reference viewpoint, and usingthe light field image data and the depth map to synthesize an image fromthe reference viewpoint. The synthesized image can then be compressedfor storage. The depth map and additional data that can be utilized inthe post processing can also be encoded as metadata that can be storedin the same container file with the encoded image.

A process for capturing and storing light field image data in accordancewith an embodiment of the invention is illustrated in FIG. 2. Theprocess 200 includes capturing (202) light field image data. In severalembodiments, the light field image data is captured using an arraycamera similar to the array cameras described above. In otherembodiments, any of a variety of image capture device(s) can be utilizedto capture light field image data. The light field image data is used togenerate (204) a depth map. A depth map can be generated using any of avariety of techniques including (but not limited to) using any of theprocesses disclosed in U.S. Provisional Patent Application Ser. No.61/691,666 or U.S. patent application Ser. No. 13/623,091 entitled“Systems and Methods for Determining Depth from Multiple Views of aScene that Include Aliasing Using Hypothesized Fusion”, to Venkatarmanet al. The disclosure of U.S. patent Ser. No. 13/623,091 is incorporatedby reference herein in its entirety.

The light field image data and the depth map can be utilized tosynthesize (206) an image from a specific viewpoint. In manyembodiments, the light field image data includes a number of lowresolution images that are used to synthesize a higher resolution imageusing a super resolution process. In a number of embodiments, a superresolution process such as (but not limited to) any of the superresolution processes disclosed in U.S. patent application Ser. No.12/967,807 can be utilized to synthesize a higher resolution image fromthe reference viewpoint.

In order to be able to perform post processing to modify the synthesizedimage without the original light field image data, metadata can begenerated (208) from the light field image data, the synthesized image,and/or the depth map. The metadata data can be included in a light fieldimage file and utilized during post processing of the synthesized imageto perform processing including (but not limited to) refocusing theencoded image based upon a focal plane specified by the user, andsynthesizing one or more images from a different viewpoint. In a numberof embodiments, the auxiliary data includes (but is not limited to)pixels in the light field image data occluded from the referenceviewpoint used to synthesize the image from the light field image data,one or more auxiliary maps including (but not limited to) a confidencemap, an edge map, and/or a missing pixel map. Auxiliary data that isformatted as maps or layers provide information corresponding to pixellocations within the synthesized image. A confidence map is producedduring the generation of a depth map and reflects the reliability of thedepth value for a particular pixel. This information may be used toapply different filters in areas of the image and improve image qualityof the rendered image. An edge map defines which pixels are edge pixels,which enables application of filters that refine edges (e.g. postsharpening). A missing pixel map represents pixels computed byinterpolation of neighboring pixels and enables selection ofpost-processing filters to improve image quality. As can be readilyappreciated, the specific metadata generated depends upon the postprocessing supported by the image data file. In a number of embodiments,no auxiliary data is included in the image data file.

In order to generate an image data file, the synthesized image isencoded (210). The encoding typically involves compressing thesynthesized image and can involve lossless or lossy compression of thesynthesized image. In many embodiments, the depth map and any auxiliarydata are written (212) to a file with the encoded image as metadata togenerate a light field image data file. In a number of embodiments, thedepth map and/or the auxiliary maps are encoded. In many embodiments,the encoding involves lossless compression.

Although specific processes for encoding light field image data forstorage in a light field image file are discussed above, any of avariety of techniques can be utilized to process light field image dataand store the results in an image file including but not limited toprocesses that encode low resolution images captured by an array cameraand calibration information concerning the array camera that can beutilized in super resolution processing. Storage of light field imagedata in JFIF files in accordance with embodiments of the invention isdiscussed further below.

Image Data Formats

In several embodiments, the encoding of a synthesized image and thecontainer file format utilized to create the light field image file arebased upon standards including but not limited to the JPEG standard(ISO/IEC 10918-1) for encoding a still image as a bitstream and the JFIFstandard (ISO/IEC 10918-5). By utilizing these standards, thesynthesized image can be rendered by any rendering device configured tosupport rendering of JPEG images contained within JFIF files. In manyembodiments, additional data concerning the synthesized image such as(but not limited to) a depth map and auxiliary data that can be utilizedin the post processing of the synthesized image can be stored asmetadata associated with an Application marker within the JFIF file.Conventional rendering devices can simply skip Application markerscontaining this metadata. Rendering device in accordance with manyembodiments of the invention can decode the metadata and utilize themetadata in any of a variety of post processing processes.

A process for encoding an image synthesized using light field image datain accordance with the JPEG specification and for including the encodedimage and metadata that can be utilized in the post processing of theimage in a JFIF file in accordance with an embodiment of the inventionis illustrated in FIG. 3. The process 300 includes encoding (302) animage synthesized from light field image data in accordance with theJPEG standard. The image data is written (304) to a JFIF file. A depthmap for the synthesized image is compressed (306) and the compresseddepth map and any additional auxiliary data are written (308) asmetadata to an Application marker segment of the JFIF file containingthe encoded image. Where the auxiliary data includes maps, the maps canalso be compressed by encoding the maps in accordance with the JPEGstandard. At which point, the JFIF file contains an encoded image andmetadata that can be utilized to perform post processing on the encodedimage in ways that utilize the additional information captured in thelight field image data utilized to synthesize the high resolution image(without the need to perform super resolution processing on theunderlying light field image data).

Although specific processes are discussed above for storing light fieldimage data in JFIF files, any of a variety of processes can be utilizedto encode synthesized images and additional metadata derived from thelight field image data used to synthesize the encoded images in a JFIFfile as appropriate to the requirements of a specific application inaccordance with embodiments of the invention. The encoding ofsynthesized images and metadata for insertion into JFIF files inaccordance with embodiments of the invention are discussed furtherbelow. Although much of the discussion that follows relates to JFIFfiles, synthesized images and metadata can be encoded for inclusion in alight field image file using any of a variety of proprietary orstandards based encoding techniques and/or utilizing any of a variety ofproprietary or standards based file formats.

Encoding Images Synthesized from Light Field Image Data

An image synthesized from light field image data using super resolutionprocessing can be encoded in accordance with the JPEG standard forinclusion in a light field image file in accordance with embodiments ofthe invention. The JPEG standard is a lossy compression standard.However, the information losses typically do not impact edges ofobjects. Therefore, the loss of information during the encoding of theimage typically does not impact the accuracy of maps generated basedupon the synthesized image (as opposed to the encoded synthesizedimage). The pixels within images contained within files that comply withthe JFIF standard are typically encoded as YCbCr values. Many arraycameras synthesize images, where each pixel is expressed in terms of aRed, Green and Blue intensity value. In several embodiments, the processof encoding the synthesized image involves mapping the pixels of theimage from the RGB domain to the YCbCr domain prior to encoding. Inother embodiments, mechanisms are used within the file to encode theimage in the RGB domain. Typically, encoding in the YCbCr domainprovides better compression ratios and encoding in the RGB domainprovides higher decoded image quality.

Storing Additional Metadata Derived from Light Field Image Data

The JFIF standard does not specify a format for storing depth maps orauxiliary data generated by an array camera. The JFIF standard does,however, provide sixteen Application markers that can be utilized tostore metadata concerning the encoded image contained within the file.In a number of embodiments, one or more of the Application markers of aJFIF file is utilized to store an encoded depth map and/or one or moreauxiliary maps that can be utilized in the post processing of theencoded image contained within the file.

A JFIF Application marker segment that can be utilized to store a depthmap, individual camera occlusion data and auxiliary map data inaccordance with an embodiment of the invention is illustrated in FIG. 4.The APP9 Application marker segment 400 uses a format identifier 402that uniquely identifies that the Application marker segment containsmetadata describing an image synthesized using light field image data.In a number of embodiments, the identifier is referred to as the “DZFormat Identifier” 402 and is expressed as the zero terminated string“PIDZ0”.

The Application marker segment includes a header 404 indicated as “DZHeader” that provides a description of the metadata contained within theApplication marker segment. In the illustrated embodiment, the “DZHeader” 404 includes a DZ Endian field that indicates whether the datain the “DZ Header” is big endian or little endian. The “DZ Header” 404also includes a “DZ Selection Descriptor”.

An embodiment of a “DZ Selection Descriptor” is illustrated in FIG. 5,which includes four bytes. The first two bytes (i.e. bytes 0 and 1)contain information concerning the metadata describing the encoded imagethat are present (see FIG. 6) and the manner in which the differentpieces of metadata are compressed (see FIG. 7). In the illustratedembodiment, the types of metadata that are supported are a depth map,occluded pixel data, virtual view point data, a missing pixel map, aregular edge map, a silhouette edge map, and/or a confidence map. Inother embodiments, any of a variety of metadata describing an encodedimage obtained from the light field image data used to synthesize theimage can be included in the metadata contained within a JFIF file inaccordance with an embodiment of the invention. In many instances, themetadata describing the encoded image can include maps that can beconsidered to be monochrome images that can be encoded using JPEGencoding. In a number of embodiments, the maps can be compressed usinglossless JPEG LS encoding. In several embodiments, the maps can becompressed using lossy JPEG encoding. Utilizing JPEG encoding tocompress the maps reduces the size of the maps and enables renderingdevices to leverage a JPEG decoder to both decode the image containedwithin the JFIF file and the maps describing the encoded image. Thethird byte (i.e. byte 2) of the “DZ Selection Descriptor” indicates thenumber of sets of metadata describing the encoded image that arecontained within the Application marker segment and the fourth byte isreserved. Although specific implementations of the header 404 describingthe metadata contained within the Application marker segment areillustrated in FIGS. 4-7, any of a variety of implementations can beutilized to identify the maps describing the synthesized image that arepresent within the metadata contained within an light field image fileas appropriate to the requirements of the application in accordance withembodiments of the invention.

Depth Map

Referring back to FIG. 4, the Application marker segment also includes a“Depth Map Header” 406 that describes depth map 416 included within theApplication marker segment. The “Depth Map Header”406 includes anindication 408 of the size of “Depth Map Attributes” 410 included withinthe “Depth Map Header”, the “Depth Map Attributes” 410, and a “Depth MapDescriptor” 412. As noted above, the depth map 416 can be considered tobe a monochrome image and lossless or lossy JPEG encoding can beutilized to compress the “Depth Map Data” included in a JFIF file.

A “Depth Map Attributes” table in accordance with an embodiment of theinvention is illustrated in FIG. 8 and includes information concerningthe manner in which the depth map should be used to render the encodedimage. In the illustrated embodiment, the information contained withinthe “Depth Map Attributes” table includes the focal plane and the F# ofthe synthetic aperture to utilize when rendering the encoded image.Although specific pieces of information related to the manner in whichthe depth map can be utilized to render the encoded image areillustrated in FIG. 8, any of a variety of pieces of informationappropriate to the requirements of a specific application can beutilized in accordance with embodiments of the invention.

A “Depth Map Descriptor” in accordance with an embodiment of theinvention is illustrated in FIG. 9 and includes metadata describing thedepth map. In the illustrated embodiment, the “Depth Map Descriptor”includes a zero terminated identifier string “PIDZDH0” and versioninformation. In other embodiments, any of a variety of pieces ofinformation appropriate to the specific requirements of particularapplications can be utilized in accordance with embodiments of theinvention.

A JFIF Application marker segment is restricted to 65,533 bytes.However, an Application marker can be utilized multiple times within aJFIF file. Therefore, depth maps in accordance with many embodiments ofthe invention can span multiple APP9 Application marker segments. Themanner in which depth map data is stored within an Application markersegment in a JFIF file in accordance with an embodiment of the inventionis illustrated in FIG. 10. In the illustrated embodiment, the depth mapdata is contained within a descriptor that is uniquely identified usingthe “PIDZDD0” zero terminated string. The descriptor also includes thelength of the descriptor and depth map data.

Although specific implementations of a depth map and header describing adepth map within an Application marker segment of a JFIF file areillustrated in FIGS. 4, 8, 9, and 10, any of a variety ofimplementations can be utilized to include a depth map describing anencoded image within a JFIF file as appropriate to the requirements ofthe application in accordance with embodiments of the invention.

Occlusion Data

Referring back to FIG. 4, the Application marker segment also includes a“Camera Array Header” 418 that describes occlusion data 428 forindividual cameras within an array camera that captured the light fieldimage data utilized to synthesize the image contained within the lightfield image file. The occlusion data can be useful in a variety of postprocessing processes including (but not limited) to process that involvemodifying the viewpoint of the encoded image. The “Camera Array Header”418 includes an indication 420 of the size of a “Camera Array GeneralAttributes” table 422 included within the “Camera Array Header”, the“Camera Array General Attributes” table 422, and a “Camera ArrayDescriptor” 424.

A “Camera Array General Attributes” table in accordance with anembodiment of the invention is illustrated in FIG. 11 and includesinformation describing the number of cameras and dimensions of a cameraarray utilized to capture the light field image data utilized tosynthesize the image encoded within the JFIF file. In addition, the“Camera Array General Attributes” table can indicate a reference cameraposition within the array and/or a virtual view position within thearray. The “Camera Array General Attributes” table also providesinformation concerning the number of cameras within the array for whichocclusion data is provided within the JFIF file.

A “Camera Array Descriptor” in accordance with an embodiment of theinvention is illustrated in FIG. 12 and includes metadata describing theindividual camera occlusion data contained within the JFIF file. In theillustrated embodiment, the “Camera Array Descriptor” includes a zeroterminated identifier string “PIDZAH0” and version information. In otherembodiments, any of a variety of pieces of information appropriate tothe specific requirements of particular applications can be utilized inaccordance with embodiments of the invention.

In many embodiments, occlusion data is provided on a camera by camerabasis. In several embodiments, the occlusion data is included within aJFIF file using an individual camera descriptor and an associated set ofocclusion data. An individual camera descriptor that identifies a cameraand identifies the number of occluded pixels related to the identifiedcamera described within the JFIF file in accordance with an embodimentof the invention is illustrated in FIG. 13. In the illustratedembodiment, the descriptor is identified using the “PIDZCD0” zeroterminated string. The descriptor also includes a camera number that canbe utilized to identify a camera within an array camera that capturedlight field image data utilized to synthesize the encoded imagecontained within the JFIF file. In addition, the descriptor includes thenumber of occluded pixels described in the JFIF file and the length (inbytes) of the data describing the occluded pixels. The manner in whichthe occluded pixel data can be described in accordance with embodimentsof the invention is illustrated in FIG. 14. The same descriptor“PDIZCD0” is used to identify the occluded pixel data and the descriptoralso includes the number of pixels of occluded data contained within thesegment, the length of the data in bytes and an offset to the nextmarker in addition to the occluded pixel data. Due to the restriction onApplication marker segments not exceeding 65,533 bytes in data, theadditional information enables a rendering device to reconstruct theoccluded pixel data across multiple APP9 application marker segmentswithin a JFIF file in accordance with embodiments of the invention.

A table describing an occluded pixel that can be inserted within a JFIFfile in accordance with an embodiment of the invention is illustrated inFIG. 15. The table includes the depth of the occluded pixel, the pixelcolor of the occluded pixel and the pixel coordinates. In theillustrated embodiment, the pixel color is illustrated as being in theRGB domain. In other embodiments, the pixel color can be expressed inany domain including the YCbCr domain.

Although specific implementations for storing information describingoccluded pixel depth within an Application marker segment of a JFIF fileare illustrated in FIGS. 4, 13, 14, and 15, any of a variety ofimplementations can be utilized to include occluded pixel informationwithin a JFIF file as appropriate to the requirements of the applicationin accordance with embodiments of the invention.

Auxiliary Maps

Referring back to FIG. 4, any of a variety of auxiliary maps can beincluded in an Application marker segment within a JFIF file inaccordance with an embodiment of the invention. The total number ofauxiliary maps and the types of auxiliary maps can be indicated in theApplication marker segment. Each auxiliary map can be expressed using an“Auxiliary Map Descriptor” 432 and “Auxiliary Map Data” 434. In theillustrated embodiment, the “Auxiliary Map Descriptor” 432 is includedin an “Auxiliary Map Header” 430 within the Application marker segmentin the JFIF file.

An “Auxiliary Map Descriptor” that describes an auxiliary map containedwithin a light field image file in accordance with an embodiment of theinvention is illustrated in FIG. 16. The “Auxiliary Map Descriptor”includes an identifier, which is the “PIDZAM0” zero terminated stringand information specifying the type of auxiliary map and number of bitsper pixel in the map. As noted above, any of a variety of auxiliary mapsderived from light field image data used to synthesize an encoded imagecan be included within a JFIF file in accordance with embodiments of theinvention. In the illustrated embodiment, confidence maps, silhouetteedge maps, regular edge maps, and missing pixel maps are supported.

“Auxiliary Map Data” stored in a JFIF file in accordance with anembodiment of the invention is conceptually illustrated in FIG. 17. The“Auxiliary Map Data” uses the same “PDIZAD0” zero terminated stringidentifier and includes the number of pixels of the auxiliary mapcontained within the segment, the length of the data in bytes and anoffset to the next marker in addition to pixels of the auxiliary map.Due to the restriction on Application marker segments not exceeding65,533 bytes in data, the additional information enables a renderingdevice to reconstruct the auxiliary map describing the encoded imageacross multiple APP9 application marker segments within a JFIF file.

Although specific implementations for storing auxiliary maps within anApplication marker segment of a JFIF file are illustrated in FIGS. 4,16, and 17, any of a variety of implementations can be utilized toinclude auxiliary map information within a JFIF file as appropriate tothe requirements of the application in accordance with embodiments ofthe invention. Various examples of auxiliary maps that can be utilizedto provide additional information concerning an encoded image based uponthe light field image data utilized to synthesize the encoded image inaccordance with embodiments of the invention are discussed below.

Confidence Maps

A confidence map can be utilized to provide information concerning therelative reliability of the information at a specific pixel location. Inseveral embodiments, a confidence map is represented as a complimentaryone bit per pixel map representing pixels within the encoded image thatwere visible in only a subset of the images used to synthesize theencoded image. In other embodiments, a confidence map can utilizeadditional bits of information to express confidence using any of avariety of metrics including (but not limited to) a confidence measuredetermined during super resolution processing, or the number of imagesin which the pixel is visible.

Edge Maps

A variety of edge maps can be provided included (but not limited to) aregular edge map and a silhouette map. A regular edge map is a map thatidentifies pixels that are on an edge in the image, where the edge is anintensity discontinuity. A silhouette edge maps is a map that identifiespixels that are on an edge, where the edge involves an intensitydiscontinuity and a depth discontinuity. In several embodiments, eachcan be expressed as a separate one bit map or the two maps can becombined as a map including two pixels per map. The bits simply signalthe presence of a particular type of edge at a specific location to postprocessing processes that apply filters including (but not limited to)various edge preserving and/or edge sharpening filters.

Missing Pixel Maps

A missing pixel map indicates pixel locations in a synthesized imagethat do not include a pixel from the light field image data, but insteadinclude an interpolated pixel value. In several embodiments, a missingpixel map can be represented using a complimentary one bit per pixelmap. The missing pixel map enables selection of post-processing filtersto improve image quality. In many embodiments, a simple interpolationalgorithm can be used during the synthesis of a higher resolution fromlight field image data and the missing pixels map can be utilized toapply a more computationally expensive interpolation process as a postprocessing process. In other embodiments, missing pixel maps can beutilized in any of a variety of different post processing process asappropriate to the requirements of a specific application in accordancewith embodiments of the invention.

Rendering Images Using Light Field Imaging Files

When light field image data is encoded in a light field image file, thelight field image file can be shared with a variety of rendering devicesincluding but not limited to cameras, mobile devices, personalcomputers, tablet computers, network connected televisions, networkconnected game consoles, network connected media players, and any otherdevice that is connected to the Internet and can be configured todisplay images. A system for sharing light field image files inaccordance with an embodiment of the invention is illustrated in FIG.18. The system 1800 includes a mobile device 1802 including an arraycamera configured to capture light field image data and encode the lightfield image data in a light field image file. The mobile device 1802also includes a network interface that enables the transfer of a lightfield image file to other rendering devices via the Internet 1804. Inseveral embodiments, the light field image file is transferred with theassistance of a server system 1806 that can either store the light fieldimage file for access by other devices or relay the light field imagefile to other rendering devices. In many embodiments, the server system1806 provides a user interface that enables users to modify therendering of the image provided to the device. In several embodiments,the server system 1806 provides the light field image file to a devicefor rendering. In the illustrated embodiment, a variety of networkconnected rendering devices 1808 are illustrated including a mobilephone and a personal computer. In other embodiments, any of a variety ofnetwork connected and/or disconnected devices can render images using alight field image file in accordance with embodiments of the invention.Rendering devices and processes for rendering images in accordance withembodiments of the invention are discussed further below.

Rendering Devices

A rendering device in accordance with embodiments of the inventiontypically includes a processor and a rendering application that enablesthe rendering of an image based upon a light field image data file. Thesimplest rendering is for the rendering device to decode the encodedimage contained within the light field image data file. More complexrenderings involve applying post processing to the encoded image usingthe metadata contained within the light field image file to performmanipulations including (but not limited to) modifying the viewpoint ofthe image and/or modifying the focal plane of the image.

A rendering device in accordance with an embodiment of the invention isillustrated in FIG. 19. The rendering device 1900 includes a processor1902, memory 1904, and an optional network interface 1906. The memorycontains a rendering application 1908 that is used to configure themicroprocessor to render images for display using a light field imagefile 1910. In the illustrated embodiment, the light field image file isshown stored in memory. In other embodiments, the light field image filecan be stored in an external storage device. Although a specificrendering device is illustrated in FIG. 19, any of a variety ofrendering devices can be utilized in accordance with embodiments of theinvention including (but not limited to) the types of devices that arecustomarily used to display images using image files. Processes forrendering of images using light field image files in accordance withembodiments of the invention are discussed further below.

Processes for Rendering Images Using Light Field Image Files

As noted above, rendering a light field image file can be as simple asdecoding an encoded image contained within the light field image file orcan involve more complex post processing of the encoded image usingmetadata derived from the same light field image data used to synthesizethe encoded image. A process for rendering a light field image inaccordance with an embodiment of the invention is illustrated in FIG.20. The process 2000 includes parsing (2002) the light field image fileto locate the encoded image contained within the image file. The encodedimage file is decoded (2004). As noted above, the image can be encodedusing a standards based encoder and so the decoding process can utilizea standards based codec within a rendering device, or the image can beencoded using a proprietary encoding and a proprietary decoder isprovided on the rendering device to decode the image. When the processfor rendering the image simply involves rendering the image, the decodedimage can be displayed. When the process for rendering the imageincludes post processing, the image file is parsed (2006) to locatemetadata within the file that can be utilized to perform the postprocessing. The metadata is decoded (2008). The metadata can often takethe form of maps that can be encoded using standards based imageencoders and a standards based decoder present on the rendering devicecan be utilized to decode the metadata. In other embodiments, aproprietary decoding process is utilized to decode the metadata. Themetadata can then be used to perform (2010) the post processing of theencoded image and the image can be displayed (2012). The display of theimage can be local. Alternatively the image can be streamed to a remotedevice or encoded as an image and provided to a remote device fordisplay.

Although specific processes for rendering an image from a light fieldimage file are discussed with reference to FIG. 20, any of a variety ofprocesses appropriate to the requirements of a specific application canbe utilized to render an image for display using a light field imagefile in accordance with an embodiment of the invention. As noted above,any of a variety of standards based encoders and decoders can beutilized in the encoding and decoding of light field image files inaccordance with embodiments of the invention. Processes for renderingimages using light field image files that conform to the JFIF standardand include an image and/or metadata encoded in accordance with the JPEGstandard are discussed further below.

Rendering Images Using JFIF Light Field Image Files

The ability to leverage deployed JPEG decoders can greatly simplify theprocess of rendering light field images. When a light field image fileconforms to the JFIF standard and the image and/or metadata encodedwithin the light field image file is encoded in accordance with the JPEGstandard, a rendering application can leverage an existingimplementation of a JPEG decoder to render an image using the lightfield image file. Similar efficiencies can be obtained where the lightfield image file includes an image and/or metadata encoded in accordancewith another popular standard for image encoding.

A rendering device configured by a rendering application to render animage using a light field image file in accordance with an embodiment ofthe invention is illustrated in FIG. 21. The rendering device 2100includes a processor 2102, memory 2104, and an optional networkinterface 2106 that can be utilized to receive light field image files.In the illustrated embodiment, the memory 2104 of the rendering device2100 includes a rendering application 2108, a JPEG decoder application2110, and a light field image file 2112 that contains at least one imageand/or metadata encoded in accordance with the JPEG standard. Therendering application 2108 configures the processor to parse the lightfield image file to locate an encoded image and to decode the encodedimage using the JPEG decoder application 2110. Similarly, the renderingapplication can configure the processor to parse the light field imagefile to locate metadata and to decode encoded maps contained within themetadata using the JPEG decoder.

Although specific rendering devices including JPEG decoders arediscussed above with reference to FIG. 21, any of a variety of renderingdevices incorporating standards based decoders can be utilized to renderimages from appropriately encoded light field image files in accordancewith embodiments of the invention. Processes for decoding light fieldimage files that confirm with the JFIF standard and that contain atleast one image and/or metadata encoded in accordance with the JPEGstandard in accordance with embodiments of the invention are discussedfurther below.

Processes for Rendering Images from JFIF Light Field Image Files

Processes for rending images using light field image files that conformto the JFIF standard can utilize markers within the light field imagefile to identify encoded images and metadata. Headers within themetadata provide information concerning the metadata present in the fileand can provide offset information or pointers to the location ofadditional metadata and/or markers within the file to assist withparsing the file. Once appropriate information is located a standardJPEG decoder implementation can be utilized to decode encoded imagesand/or maps within the file.

A process for displaying an image rendered using a light field imagefile that conforms to the JFIF standard using a JPEG decoder inaccordance with an embodiment of the invention is illustrated in FIG.22. The process 2200 involves parsing (2202) the light field image fileto locate a Start of Image (SOI) Marker. The SOI marker is used tolocate an image file encoded in accordance with the JPEG format. Theencoded image can be decoded (2204) using a JPEG decoder. When no postprocessing of the decoded image is desired, the image can simply bedisplayed. Where post processing of the image is desired (e.g. to changethe view point of the image and/or the focal plane of the image), theprocess parses (2206) the light field image file to locate anappropriate Application marker. In the illustrated embodiment, an APP9marker indicates the presence of metadata within the light field imagefile. The specific metadata within the file can be determined by parsing(2206) a header within the APP9 Application marker segment thatdescribes the metadata within the file. In the illustrated embodiment,the header is the “DZ Header” within the APP9 Application markersegment. The information within the metadata header can be utilized tolocate (2208) specific metadata utilized in a post processing processwithin the light field image file. In instances where the metadata isencoded, the metadata can be decoded. In many embodiments, metadatadescribing an encoded image within a light field image file is in theform of a map that provides information concerning specific pixelswithin an encoded image contained within the light field image file andJPEG encoding is used to compress the map. Accordingly, a JPEG decodercan be utilized to decode the map. The decoded metadata can be utilizedto perform (2212) a post processes the decoded image. The image can thenbe displayed (2214). In many embodiments, the image is displayed on alocal display. In a number of embodiments, the image is streamed to aremote display or encoded as an image and forwarded to a remote devicefor display.

Although specific processes for displaying images rendered using lightfield image files are discussed above with respect to FIG. 22, any of avariety of processes for parsing a light field image file and decodingimages and/or metadata encoded in accordance with the JPEG standardusing a JPEG decoder can be utilized in accordance with embodiments ofthe invention. Much of the discussion above references the use ofmetadata derived from light field image data and contained within alight field image file to perform post processing processes on anencoded image synthesized from the light field image data. Postprocessing of images synthesized from light field image data usingmetadata obtained using the light field image data in accordance withembodiments of the invention are discussed further below.

Post Processing of Images Using Metadata Derived from Light Field ImageData

Images can be synthesized from light field image data in a variety ofways. Metadata included in light field image files in accordance withembodiments of the invention can enable images to be rendered from asingle image synthesized from the light field image data without theneed to perform super resolution processing. Advantages of renderingimages in this way can include that the process of obtaining the finalimage is less processor intensive and less data is used to obtain thefinal image. However, the light field image data provides richinformation concerning a captured scene from multiple viewpoints. Inmany embodiments, a depth map and occluded pixels from the light fieldimage data (i.e. pixels that are not visible from the referenceviewpoint of the synthesized image) can be included in a light fieldimage file to provide some of the additional information typicallycontained within light field image data. The depth map can be utilizedto modify the focal plane when rendering an image and/or to apply depthdependent effects to the rendered image. The depth map and the occludedpixels can be utilized to synthesize images from different viewpoints.In several embodiments, additional maps are provided (such as, but notlimited to, confidence maps, edge maps, and missing pixel maps) that canbe utilized when rendering alternative viewpoints to improve theresulting rendered image. The ability to render images from differentviewpoints can be utilized to simply render an image from a differentviewpoint. In many embodiments, the ability to render images fromdifferent viewpoints can be utilized to generate a stereo pair for 3Dviewing. In several embodiments, processes similar to those described inU.S. Provisional Patent Application Ser. No. 61/707,691, entitled“Synthesizing Images From Light Fields Utilizing Virtual Viewpoints” toJain (the disclosure of which is incorporated herein by reference in itsentirety) can be utilized to modify the viewpoint based upon motion of arendering device to create a motion parallax effect. Processes forrendering images using depth based effects and for rendering imagesusing different viewpoints are discussed further below.

Rendering Images Using Depth Based Effects

A variety of depth based effects can be applied to an image synthesizedfrom light field image data in accordance with embodiments of theinvention including (but not limited to) applying dynamic refocusing ofan image, locally varying the depth of field within an image, selectingmultiple in focus areas at different depths, and/or applying one or moredepth related blur model. A process for applying depth based effects toan image synthesized from light field image data and contained within alight field image file that includes a depth map in accordance with anembodiment of the invention is illustrated in FIG. 23. The process 2300includes decoding (2302) an image synthesized from light field imagedata contained within a light field image file. In addition, a depth mapderived from the light field image data that describes the synthesizedimage is also decoded (2304) from metadata contained within the lightfield image file. One or more depth dependent effects can then beapplied (2406) to the pixels of the decoded image based upon the depthsof the pixels indicated by the depth map. In a number of embodiments,the depth dependent effects are automatically determined by modifyingthe focal plane, and/or F number (which provides different depths offields and degree of blur in out-of-focus regions). The image can thenbe displayed (2308). In many embodiments, the image is displayed on alocal display. In a number of embodiments, the image is streamed to aremote display or encoded as an image and forwarded to a remote devicefor display.

Although specific processes for applying depth dependent effects to animage synthesized from light field image data using a depth map obtainedusing the light field image data are discussed above with respect toFIG. 23, any of a variety of processes can be utilized for extracting animage and a depth map from a light field image file and for using thedepth map to apply one or more depth dependent effects in accordancewith embodiments of the invention. Processes for rendering images fromdifferent viewpoints to the reference viewpoint of an image containedwithin a light field image file based upon a depth map and informationconcerning occluded pixels contained within the light field image filein accordance with embodiments of the invention are discussed furtherbelow.

Rendering Images Using Different Viewpoints

One of the compelling aspects of computational imaging is the ability touse light field image data to synthesize images from differentviewpoints. The ability to synthesize images from different viewpointscreates interesting possibilities including the creation of stereo pairsfor 3D applications and the simulation of motion parallax as a userinteracts with an image. Light field image files in accordance with manyembodiments of the invention can include an image synthesized from lightfield image data from a reference viewpoint, a depth map for thesynthesized image and information concerning pixels from the light fieldimage data that are occluded in the reference viewpoint. A renderingdevice can use the information concerning the depths of the pixels inthe synthesized image and the depths of the occluded images to determinethe appropriate shifts to apply to the pixels to shift them to thelocations in which they would appear from a different viewpoint.Occluded pixels from the different viewpoint can be identified andlocations on the grid of the different viewpoint that are missing pixelscan be identified and hole filling can be performed using interpolationof adjacent non-occluded pixels. In many embodiments, the quality of animage rendered from a different viewpoint can be increased by providingadditional information in the form of auxiliary maps that can be used torefine the rendering process. In a number of embodiments, auxiliary mapscan include confidence maps, edge maps, and missing pixel maps. Each ofthese maps can provide a rendering process with information concerninghow to render an image based on customized preferences provided by auser. In other embodiments, any of a variety of auxiliary informationincluding additional auxiliary maps can be provided as appropriate tothe requirements of a specific rendering process.

A process for rendering an image from a different viewpoint using alight field image file containing an image synthesized using light fieldimage data from a reference viewpoint, a depth map describing the depthof the pixels of the synthesized image, and information concerningoccluded pixels in accordance with an embodiment of the invention isillustrated in FIG. 24. The process 2400 includes decoding (2402) animage contained within a light field image file, where the image is animage synthesized from light field image data. The process also includesdecoding (2404) a depth map from the light field image file, where thedepth map was also obtained from the light field image data used tosynthesize the encoded image. Information concerning pixels from thelight field image data that are occluded in the reference viewpoint isalso obtained (2405) from the light field image file, where theinformation includes the location and depth of the occluded pixels fromthe reference viewpoint. In many embodiments, auxiliary information,including auxiliary maps that specify additional information concerningthe pixels in the encoded image, is also contained within the lightfield image file and auxiliary information useful in the rendering of animage from a different viewpoint to the reference viewpoint can beextracted and decoded (2408) from the light field image file. Using thedepth map and the depths of the occluded pixels, shifts in the locationand depths of pixels in the different viewpoint can be determined(2410). Based upon the shifts, occluded pixels can be determined (2414)and the image displayed. Where auxiliary information is available, theauxiliary information can be utilized to adjust (2412) the pixels in theimage prior to rendering. In many embodiments, the adjustments areperformed prior to identifying occluded pixels and displaying the finalimage. In a number of embodiments, the adjustments are performed afteroccluded pixels are identifies.

Although specific processes for rendering an image from a differentviewpoint using an image synthesized from a reference view point usinglight field image data, a depth map obtained using the light field imagedata, and information concerning pixels in the light field image datathat are occluded in the reference viewpoint are discussed above withrespect to FIG. 24, any of a variety of processes can be utilized forrendering images from different viewpoints using a light field imagefile as appropriate to the requirements of specific applications inaccordance with embodiments of the invention. Processes for renderingimages simulating different lens characteristics from in accordance withembodiments of the invention are discussed further below.

While the above description contains many specific embodiments of theinvention, these should not be construed as limitations on the scope ofthe invention, but rather as an example of one embodiment thereof.Accordingly, the scope of the invention should be determined not by theembodiments illustrated, but by the appended claims and theirequivalents.

What is claimed:
 1. A system for rendering an image using a light fieldimage file including an encoded image and metadata describing theencoded image, where the metadata comprises a depth map that specifiesdepths from the reference viewpoint for pixels in the encoded image, thesystem comprising: a processor; and memory containing a renderingapplication and a light field image file including an encoded image andmetadata describing the encoded image, where the encoded image is animage of a scene synthesized from a reference viewpoint using aplurality of lower resolution images that capture the scene fromdifferent viewpoints and the metadata comprises a depth map thatspecifies depths from the reference viewpoint for pixels in the encodedimage, and pixels from the lower resolution images that are occluded inthe reference viewpoint; wherein the rendering application configuresthe processor to: locate the encoded image within the light field imagefile; decode the encoded image; locate the metadata within the lightfield image file; and post process the decoded image by modifying thepixels based on the depths indicated within the depth map to create arendered image by rendering an image from a different viewpoint usingthe depth map and the pixels from the lower resolution images that areoccluded in the reference viewpoint.
 2. The system of claim 1, whereinthe rendering application configuring the processor to post process thedecoded image by modifying the pixels based on the depths indicatedwithin the depth map to create the rendered image comprises applying adepth based effect to the pixels of the decoded image.
 3. The system ofclaim 2, wherein the depth based effect comprises at least one effectselected from the group consisting of: modifying the focal plane of thedecoded image; modifying the depth of field of the decoded image;modifying the blur in out-of-focus regions of the decoded image; locallyvarying the depth of field of the decoded image; creating multiple focusareas at different depths within the decoded image; and applying a depthrelated blur.
 4. The system of claim 2, wherein the metadata is locatedwithin an Application marker segment within the light field image file.5. The system of claim 4, wherein the Application marker segment isidentified using the APP9 marker.
 6. The system of claim 4, wherein: thedepth map is encoded in accordance with the JPEG standard using losslesscompression; and the rendering application configures the processor to:locate at least one Application marker segment containing the metadatacomprising the depth map; and decode the depth map using the JPEGdecoder.
 7. The system of claim 4, wherein: the metadata in the lightfield image file includes descriptions of the pixels from the lowerresolution images that are occluded in the reference viewpoint includingthe color, location, and depth of the occluded pixels; and rendering animage from a different viewpoint using the depth map and the pixels fromthe lower resolution images that are occluded in the reference viewpointfurther comprises: shifting pixels from the decoded image and theoccluded pixels in the metadata to the different viewpoint based uponthe depths of the pixels; determining pixel occlusions; and generatingan image from the different viewpoint using the shifted pixels that arenot occluded and by interpolating to fill in missing pixels usingadjacent pixels that are not occluded.
 8. The system of claim 4, whereinthe image rendered from the different viewpoint is part of a stereo pairof images.
 9. The system of claim 4, wherein: the metadata in the lightfield image file further comprises a confidence map for the depth map,where the confidence map indicates the reliability of the depth valuesprovided for pixels by the depth map; and rendering an image from adifferent viewpoint using the depth map and the pixels from the lowerresolution images that are occluded in the reference viewpoint furthercomprises applying at least one filter based upon the confidence map.10. The system of claim 4, wherein: the metadata in the light fieldimage file further comprises an edge map that indicates pixels in thedecoded image that lie on a discontinuity; and rendering an image from adifferent viewpoint using the depth map and the pixels from the lowerresolution images that are occluded in the reference viewpoint furthercomprises applying at least one filter based upon the edge map.
 11. Thesystem of claim 10, wherein the edge map identifies whether a pixel lieson an intensity discontinuity.
 12. The system of claim 10, wherein theedge map identifies whether a pixel lies on an intensity and depthdiscontinuity.
 13. The system of claim 10, wherein: the edge map isencoded in accordance with the JPEG standard using lossless compression;and the rendering application configures the processor to: locate atleast one Application marker segment containing the metadata comprisingthe edge map; and decode the edge map using the JPEG decoder.
 14. Thesystem of claim 4, wherein: the metadata in the light field image filefurther comprises a missing pixel map that indicates pixels in thedecoded image that do not correspond to a pixel from the plurality oflow resolution images of the scene and that are generated byinterpolating pixel values from adjacent pixels in the synthesizedimage; and rendering an image from a different viewpoint using the depthmap and the pixels from the lower resolution images that are occluded inthe reference viewpoint further comprises ignoring pixels based upon themissing pixel map.
 15. The system of claim 14, wherein: the missingpixel map is encoded in accordance with the JPEG standard using losslesscompression; and the rendering application configures the processor to:locate at least one Application marker segment containing the metadatacomprising the missing pixel; and decode the missing pixel map using theJPEG decoder.
 16. A method of for rendering an image using a light fieldimage file including an encoded image and metadata describing theencoded image, where the encoded image is an image of a scenesynthesized from a reference viewpoint using a plurality of lowerresolution images that capture the scene from different viewpoints andthe metadata comprises a depth map that specifies depths from thereference viewpoint for pixels in the encoded image, and pixels from thelower resolution images that are occluded in the reference viewpoint,the method comprising: locating said encoded image within said lightfield image file using a rendering device; decoding the encoded imageusing the rendering device; locating the metadata within the light fieldimage file using the rendering device; and post processing the decodedimage by modifying the pixels based on the depths indicated within thedepth map and the pixels from the lower resolution images that areoccluded in the reference viewpoint to create a rendered image using therendering.
 17. The method of claim 16, wherein post processing thedecoded image by modifying the pixels based on the depths indicatedwithin the depth map to create the rendered image comprises applying adepth based effect to the pixels of the decoded image using the rendingdevice.
 18. The method of claim 17, wherein the depth based effectcomprises at least one effect selected from the group consisting of:modifying the focal plane of the decoded image using the renderingdevice; modifying the depth of field of the decoded image using therendering device; modifying the blur in out-of-focus regions of thedecoded image using the rendering device; locally varying the depth offield of the decoded image using the rendering device; creating multiplefocus areas at different depths within the decoded image using therendering device; and applying a depth related blur using the renderingdevice.
 19. A non-transitory machine readable medium containingprocessor instructions, where execution of the instructions by aprocessor causes the processor to perform a process comprising: locatingan encoded image within a light field image file, where the light fieldimage file includes an encoded image that is an image of a scenesynthesized from a reference viewpoint using a plurality of lowerresolution images that capture the scene from different viewpoints andmetadata describing the encoded image comprising a depth map thatspecifies depths from the reference viewpoint for pixels in the encodedimage, and pixels from the lower resolution images that are occluded inthe reference viewpoint; decoding the encoded image; locating themetadata within the light field image file; and post processing thedecoded image by modifying the pixels based on the depths indicatedwithin the depth map and the pixels from the lower resolution imagesthat are occluded in the reference viewpoint to create a rendered image.20. The system of claim 1, wherein: the metadata in the light fieldimage file includes descriptions of the pixels from the lower resolutionimages that are occluded in the reference viewpoint including the color,location, and depth of the occluded pixels; and rendering an image froma different viewpoint using the depth map and the pixels from the lowerresolution images that are occluded in the reference viewpoint furthercomprises: shifting pixels from the decoded image and the occludedpixels in the metadata to the different viewpoint based upon the depthsof the pixels; determining pixel occlusions; and generating an imagefrom the different viewpoint using the shifted pixels that are notoccluded and by interpolating to fill in missing pixels using adjacentpixels that are not occluded.
 21. The system of claim 1, wherein theimage rendered from the different viewpoint is part of a stereo pair ofimages.
 22. The system of claim 1, wherein: the metadata in the lightfield image file further comprises a confidence map for the depth map,where the confidence map indicates the reliability of the depth valuesprovided for pixels by the depth map; and rendering an image from adifferent viewpoint using the depth map and the pixels from the lowerresolution images that are occluded in the reference viewpoint furthercomprises applying at least one filter based upon the confidence map.23. The system of claim 1, wherein: the metadata in the light fieldimage file further comprises an edge map that indicates pixels in thedecoded image that lie on a discontinuity; and rendering an image from adifferent viewpoint using the depth map and the pixels from the lowerresolution images that are occluded in the reference viewpoint furthercomprises applying at least one filter based upon the edge map.
 24. Thesystem of claim 23, wherein the edge map identifies whether a pixel lieson an intensity discontinuity.
 25. The system of claim 23, wherein theedge map identifies whether a pixel lies on an intensity and depthdiscontinuity.
 26. The system of claim 1, wherein: the metadata in thelight field image file further comprises a missing pixel map thatindicates pixels in the decoded image that do not correspond to a pixelfrom the plurality of low resolution images of the scene and that aregenerated by interpolating pixel values from adjacent pixels in thesynthesized image; and rendering an image from a different viewpointusing the depth map and the pixels from the lower resolution images thatare occluded in the reference viewpoint further comprises ignoringpixels based upon the missing pixel map.
 27. The system of claim 1,wherein: the light field image file conforms to the JFIF standard andthe encoded image is encoded in accordance with the JPEG standard; thememory comprises a JPEG decoder application; and the renderingapplication configures the processor to: locate the encoded image bylocating a Start of Image marker within the light field image file; anddecode the encoded image using the JPEG decoder.